How to add an SSH key to your computer

I spent an embarrassingly long time the other day trying to remember how to add an SSH key to my computer. The problem was that everything Google came back with involved generating an SSH key, where I had one that I needed to store on my machine so that I could get access to a server. So here are the steps I would’ve liked to find the other day:

1. Type cd into the command line to get to home folder.
2. Type cd .ssh to get into ssh folder
3. Type sublime keyfilename, where sublime can be any editor and keyfilename is whatever you want to name the key file.
4. Copy and paste the key into the file and save.
5. Profit.